quote: Dr Arnaud-Haond added that there was a theory that even asexual reproduction could not continue indefinitely because tiny "copy errors" accumulated in the genes over time.

I have never heard of such a scientific theory. Maybe the relevant scientists or anyone else could enlighten me on it. Maybe Dr Arnaud-Haond was taking aim at creationist “theories” when saying this? Also:

quote: "Most of [these errors] are expected to have a negative impact; through generations [the organism] will degenerate and eventually disappear," she said.

I’ve never seen or heard such an allegation by scientists anywhere. The only people who've ever done that were creation "scientists" in religious "articles". Again, I think that Dr Arnaud-Haond was taking aim at creationists.

quote: "The age of clonal organisms should therefore be limited as well."

Never heard of anything like it or any scientist even hinting at anything like that, except for "articles" written by creation “scientists” in creationist "journals".

quote: However, the study - which sampled seagrass across 3,500km of the Mediterranean Sea - found seagrasses with identical genomes spreading across large areas and large distances, challenging that theory.

So, I guess the researcher is challenging creationists?

quote: "We were able, through modelling, to demonstrate that Posidonia oceanica has a mode of clonal spread, common to other seagrasses, that allows the plant to avoid the accumulation of deleterious mutations and explains how it escapes this theoretical rule," Dr Arnaud-Haond observed.

quote: She said the results were one of the first times that such a long life - tens of thousands of years - had been predicted for an organism's genetic material.

I don't know of any prediction on the life-time of genetic material ever made by scientists, except for "predictions" from creation "scientists", based on some "poofing" into existence a few thousand years ago.

quote:Dr Arnaud-Haond added that there was a theory that even asexual reproduction could not continue indefinitely because tiny "copy errors" accumulated in the genes over time.

I have never heard of such a scientific theory. Maybe the relevant scientists or anyone else could enlighten me on it. Maybe Dr Arnaud-Haond was taking aim at creationist “theories” when saying this?

Isn't this idea called evolution? Mutations occur in clonal species as well, and these would have to be copy errors, right?

quote:However, the study - which sampled seagrass across 3,500km of the Mediterranean Sea - found seagrasses with identical genomes spreading across large areas and large distances, challenging that theory.

So, I guess the researcher is challenging creationists?

Actually, I find it incredibly interesting that seagrass in one spot, and sea grass in another spot, separated by thousands of km and thousands of years would be genetically identical. Mutations should have made some difference over this long of time, shouldn't it?

This may be a reference to Muller's Ratchet. However, bacteria, which are asexual, do seem to have made it through the last billion years or so.

I’ve never seen or heard such an allegation by scientists anywhere.

Me neither.

However, it is generally held that multicellular eukaryotic organisms won't last very long, because they are peculiarly vulnerable to disease. A disease which gets one of them will get them all, because they're clones of each other.

Therefore, it is a fact that such organisms tend to go extinct shortly after evolving asexuality, and so that if you use molecular clocks to measure the age of an asexual multicellular eukaryotic species, the age will be small.

The exception that proves the rule is bdeloid rotifers. They are asexual, and have been around for ages. Richard Dawkins (in The Ancestor's Tale) described their existence as an "evolutionary scandal". However, in the last year or so it's been discovered that although they don't have sex as such, they do participate in lateral gene transfer, which is a good substitute.

I think Dr Arnaud-Haond may be a little confused about what evolutionary biologists think the problem is with asexuality.

I wondered if this paper is talking about the individuals, rather than the population. Read from the angle that this is about the ageing process of individuals, the paper began to make a bit more sense.

I could be totally wrong in this, but I think that copy errors have been used to explain the ageing process of individuals along with something about telomere length wich would give individuals a finite life span. The author gives the impression that the meadow of seagrass is a single individual, rather than a population. I did a search for this author to get an idea of her area of research, but I'm none the wiser, basically because I fell asleep I'm like a bloody dormouse at this time of year.

Therefore, it is a fact that such organisms tend to go extinct shortly after evolving asexuality, and so that if you use molecular clocks to measure the age of an asexual multicellular eukaryotic species, the age will be small.

Yes. But she's talking about the age of cloning genotypes within a species that reproduces both sexually and asexually. And:

D.A. writes:

I think Dr Arnaud-Haond may be a little confused about what evolutionary biologists think the problem is with asexuality.

I saw no signs of confusion, nor of Pressie's suggestion that she was parodying creationists. The paper's interesting, but there's nothing particularly special or controversial about it at all. It merely suggests that clonal genotypes in plants like the sea grasses may well last much longer than was previously thought, and that this might be to do with phenotypic plasticity in the successful clones (which seems to makes sense).

So, it's an interesting piece of research, but I see nothing particularly special about it, and no particular relation to creationism, unless you want to use the research to show YECs that there are cloning genotypes of grass in the Med that are older than this planet.

Well, if she's talking about Muller's Ratchet, then that's not a reason why asexual organisms should go extinct, because they don't. But if she's talking about the handicap that asexual multicellular organisms suffer in the Red Queen's Race, then she's not talking about Muller's Ratchet. It seemed to me that she's conflating the two and so being wrong about both.

quote:Well, if she's talking about Muller's Ratchet, then that's not a reason why asexual organisms should go extinct, because they don't.

It certainly is a reason why asexual organisms might go extinct. Asexual organisms with small populations, that is. Which is why they write in the paper, "Reaching such an old age has been suggested to have at least two major evolutionary implications for a clonal lineage. One is the lack or limited accumulation of deleterious mutations that would otherwise eventually lead to extinction: the so called “Muller's ratchet”, which is predicted under certain population parameters. Our results suggest that this accumulation might be limited or hampered due to large population size, as well as by the persistent dominance of the original genotype under a pure regime of clonal growth demonstrated by the present model (Fig. 4)."

quote:But if she's talking about the handicap that asexual multicellular organisms suffer in the Red Queen's Race, then she's not talking about Muller's Ratchet. It seemed to me that she's conflating the two and so being wrong about both.

Where did she conflate them? The authors do list both Muller's ratchet and inability to adapt to parasites as dangers that clonal organisms need to avoid (in the paper's introduction), but I see no suggestion that they have them confused.

Well, if she's talking about Muller's Ratchet, then that's not a reason why asexual organisms should go extinct, because they don't.

She would agree. I think the article's misleading, as the Muller's ratchet angle isn't central to the paper at all. It's only mentioned in passing, and she thinks that strong conservative selection on the successful cloning genotypes deals with it.

She thinks that the clonal strains can do well for such a long time spread over different micro-environments because "general purpose genotypes" with "large phenotypic plasticity" have been selected for, despite the Red Queen disadvantage.

The article doesn't give a very good idea of the paper at all (as is often the case).

For example, here's a sentence from the journalist, followed by a quote from her:

quote:The researcher added that the plants' extreme longevity also indicated that the species displayed an ability to adapt in order to survive over such a length of time.

"The estimated age of Posidonia oceanica clones imply these have been surviving under a broad range of environmental conditions, including much lower sea-water temperatures than those recorded nowadays, showing therefore extraordinary adaptive capacities."

He incorrectly uses the word "species" when she's talking about the clones within a species. She's talking about how the same genotype is adapting through phenotypic plasticity, and he doesn't even mention that phrase in the article.

I have a suspicion that she'd probably like to strangle him for leaving out almost all of the important things she probably explained to him.

It certainly is a reason why asexual organisms might go extinct. Asexual organisms with small populations, that is.

Well any small enough population will be wiped out by genetic drift. Yes, if they're asexual, M.R. will be part of that.

Where did she conflate them? The authors do list both Muller's ratchet and inability to adapt to parasites as dangers that clonal organisms need to avoid (in the paper's introduction), but I see no suggestion that they have them confused.

I was just talking about the quotes that have been quoted from the article, I haven't read the paper. The quotes are in fact confused, which is why they confused Pressie.

quote:Well any small enough population will be wiped out by genetic drift. Yes, if they're asexual, M.R. will be part of that.

Yes, but "small enough" is probably a lot smaller for sexual (or at least recombining) populations than for asexual ones. So if you're studying the persistence of small clonal populations, it's perfectly reasonable to ask how Muller's Ratchet is being avoided.

quote:I was just talking about the quotes that have been quoted from the article, I haven't read the paper. The quotes are in fact confused, which is why they confused Pressie.

Yes, I know, but I still don't see what's confused about the quotations. The only quotation that looks peculiar to me is, ""The age of clonal organisms should therefore be limited as well," because I can't tell what is meant by age or organism in it, since it presented without any context.

Yes, I know, but I still don't see what's confused about the quotations. The only quotation that looks peculiar to me is, ""The age of clonal organisms should therefore be limited as well," because I can't tell what is meant by age or organism in it, since it presented without any context.

There's that, and also the bit I quoted further on that should have a mention of phenotypic plasticity to explain what she means by the clones adapting.

But look at the whole section with the quote you mention:

quote:Dr Arnaud-Haond added that there was a theory that even asexual reproduction could not continue indefinitely because tiny "copy errors" accumulated in the genes over time.

"Most of [these errors] are expected to have a negative impact; through generations [the organism] will degenerate and eventually disappear," she said.

"The age of clonal organisms should therefore be limited as well."

The journalist has probably missed out key phrases like "under certain population parameters" which she uses in the paper, and probably said to him on the phone. Including that might have prevented Pressie from thinking she was referring to some kind of YEC version of Muller's ratchet.

We on this board might be hypersensitive to anything that seems to smack of creationism. French scientists sitting in one of the least religious cultures of the world probably hardly ever think about it, and would fall about laughing if informed that 40% of Americans think the world is less than ten thousand years old.

I do think it's shoddy journalism, but that's common. The reason I titled my first reply "end of topic" was because I'd read the paper which has none of these problems.

The original article is about individual organisms to have been living for thousands of years, while the report by the BBC mentions some law about "species" that can't be long-lived.

quote:He incorrectly uses the word "species" when she's talking about the clones within a species. She's talking about how the same genotype is adapting through phenotypic plasticity, and he doesn't even mention that phrase in the article.

I bet that some quote from this BBC report will end up on some pseudoscience website where there will be a new "Law of Species-Longativity"; implying that researchers say that all species are very short-lived, will all die out soon and therefore creation by Allah or the FSM or whatever less than 10 000 years ago is "scientific".

The original article is about individual organisms to have been living for thousands of years, while the report by the BBC mentions some law about "species" that can't be long-lived.

Confusingly, it's about specific genotypes lasting for a very long time through cloning, rather than single individual organisms. So that some of the modern grasses are (virtually) genetically identical twins to ones that would have been there thousands and perhaps tens of thousands of years ago, because they're the result of unbroken lineages of asexual reproduction.

The Muller's ratchet theory could prevent this in certain models of growth with certain population parameters but does not inevitably do so. (It is true that creationists do sometimes misinterpret Muller's ratchet).

I can see why the presentation in the article confused you. I'm glad you brought it up, though, because I found the actual paper interesting. So, thanks back to you!